When I got approved for my adsense account I had 22 Hubs with over 1000 words each on each hub. Unfortunatley Google is always updating their requirements as they do not want to have millions upon millions of users providing average quality content. The best way to get approved even though its hard to hear (at least it was for me) is to just create hubs about your topic and apply again. Keep in mind you probably only want to apply after every 5 or so hubs are created because Google will not approve you if you apply too much. Also try to make your hubs something that is original and not yet available on Google. We have all been here just don't get discouraged even after multiple attempts. Keep going you will get approved.